Alpha Centauri in Perspective — Centauri Dreams

Image: Despite the overexposure of Centauri A and B that fuses the two stars into one at top left, I like it because it reveals Proxima Centauri (shown by the arrow at bottom right), an indication of how distant this nearest star to the Sun is from the two larger stars. Credit: 1-Meter Schmidt Telescope, ESO.

Alpha Centauri in Perspective

by PAUL GILSTER on DECEMBER 27, 2012

In his new article on Alpha Centauri in Astronomy & Geophysics, Martin Beech (Campion College, University of Regina) noted that the Alpha Centauri stars seem to go through waves of scientific interest. Beech used Google’s Ngram Viewer to look for references to the system in both the scientific literature as well as general magazines and newspapers, finding that there is a 30-year interval between peaks of interest. The figure is suspiciously generational, and Beech wonders whether it reflects an awakening of interest in this nearby system as each generation of scientists and publishers arises.

I mentioned on Christmas Eve that the Beech paper was a real gift for the holidays, and for those of us who try to track developments about Alpha Centauri, it certainly is, drawing together recent work and commenting with care on the findings. The big issue for now is the existence of planets around these stars, a question Centauri B b will begin to answer if it can be confirmed. Everyone from astrophysicists to science fiction authors has noted at one time or another that we may have planets around all three of these stars, no doubt fueling that thirty-year spike Beech identified.

I remember a long-ago sixth grade afternoon when I asked the teacher, after a presentation about astronomy, whether the nearest star had planets like ours around it. After class, she slipped me a book to look at whose title is long lost to memory, but I recall it being stated with confidence that planets were all but impossible around binary stars. Now we know better, for we have planets around binaries elsewhere. As for Alpha Centauri, it was in 1997 that Paul Wiegert and Matt Holman showed that planetary orbits were viable here out to about 4 AU around Centauri A and B.

That would seem to rule out gas giants, which presumably would have formed beyond the snow line at roughly the same 4 AU and beyond, but terrestrial planets in closer orbits are still allowed. Beech runs through the recent scholarship for Centauri A and B, most of which shows the likelihood of planet formation, though in at least one case with a serious restriction: